So to my utter joy, someone took obdgpslogger seriously, and logged an entire cross-country trip with it.
He blogged about it here: http://www.rinarledge.com/, and generously has let me post the data files on my site.
The output from obdlogger: longfeltwant.db
Open this in Google Earth: longfeltwant.kml.gz [gzipped]
The CSV file: longfeltwant.csv.gz [gzipped]